(no commit message)
[oweals/gnunet.git] / src / transport / plugin_transport_tcp.c
index c77963e32a7cb23c57da7685cbe343722aa2dd94..18aad989c68dece175636b526ef2cc25e1a6fcdf 100644 (file)
@@ -26,6 +26,7 @@
 #include "gnunet_hello_lib.h"
 #include "gnunet_connection_lib.h"
 #include "gnunet_container_lib.h"
+#include "gnunet_nat_lib.h"
 #include "gnunet_os_lib.h"
 #include "gnunet_protocols.h"
 #include "gnunet_resolver_service.h"
@@ -89,6 +90,17 @@ struct TCP_NAT_ProbeMessage
  */
 struct TCPProbeContext
 {
+
+  /**
+   * Active probes are kept in a DLL.
+   */
+  struct TCPProbeContext *next;
+
+  /**
+   * Active probes are kept in a DLL.
+   */
+  struct TCPProbeContext *prev;
+
   /**
    * Probe connection.
    */
@@ -170,6 +182,27 @@ struct LocalAddrList
    */
   struct LocalAddrList *prev;
 
+  /**
+   * Link to plugin.
+   */
+  struct Plugin *plugin;
+
+  /**
+   * Handle to NAT holes we've tried to punch for this address.
+   */
+  struct GNUNET_NAT_Handle *nat;
+
+  /**
+   * Pointer to a 'struct IPv4/V6TcpAddress' describing our external IP and port
+   * as obtained from the NAT by automatic port mapping.
+   */
+  void *external_nat_address;
+
+  /**
+   * Number of bytes in 'external_nat_address'
+   */
+  size_t ena_size;
+
   /**
    * Number of bytes of the address that follow
    */
@@ -383,13 +416,15 @@ struct Plugin
   struct GNUNET_CONTAINER_MultiHashMap *nat_wait_conns;
 
   /**
-   * The external address given to us by the user.  Must be actual
-   * outside visible address for NAT punching to work.
+   * The external address given to us by the user.  Used for HELLOs
+   * and address validation.
    */
   char *external_address;
 
   /**
    * The internal address given to us by the user (or discovered).
+   * Used for NAT traversal (ICMP method), but not as a 'validateable'
+   * address in HELLOs.
    */
   char *internal_address;
 
@@ -408,6 +443,16 @@ struct Plugin
    */
   struct LocalAddrList *lal_tail;
 
+  /**
+   * List of active TCP probes.
+   */
+  struct TCPProbeContext *probe_head;
+
+  /**
+   * List of active TCP probes.
+   */
+  struct TCPProbeContext *probe_tail;
+
   /**
    * ID of task used to update our addresses when one expires.
    */
@@ -435,15 +480,80 @@ struct Plugin
   int allow_nat;
 
   /**
-   * Should this transport advertise only NAT addresses (port set to 0)?
-   * If not, all addresses will be duplicated for NAT punching and regular
-   * ports.
+   * Are we allowed to try UPnP/PMP for NAT traversal?
    */
-  int only_nat_addresses;
+  int allow_upnp;
 
 };
 
 
+/**
+ * Our external IP address/port mapping has changed.
+ *
+ * @param cls closure, the 'struct LocalAddrList'
+ * @param add_remove GNUNET_YES to mean the new public IP address, GNUNET_NO to mean
+ *     the previous (now invalid) one
+ * @param addr either the previous or the new public IP address
+ * @param addrlen actual lenght of the address
+ */
+static void
+nat_port_map_callback (void *cls,
+                      int add_remove,
+                      const struct sockaddr *addr,
+                      socklen_t addrlen)
+{
+  struct LocalAddrList *lal = cls;
+  struct Plugin *plugin = lal->plugin;
+  int af;
+  struct IPv4TcpAddress t4;
+  struct IPv6TcpAddress t6;
+  void *arg;
+  uint16_t args;
+
+  /* convert 'addr' to our internal format */
+  af = addr->sa_family;
+  switch (af)
+    {
+    case AF_INET:
+      t4.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
+      t6.t6_port = ((struct sockaddr_in *) addr)->sin_port;
+      arg = &t4;
+      args = sizeof (t4);
+      break;
+    case AF_INET6:
+      memcpy (&t6.ipv6_addr,
+             &((struct sockaddr_in6 *) addr)->sin6_addr,
+             sizeof (struct in6_addr));
+      t6.t6_port = ((struct sockaddr_in6 *) addr)->sin6_port;
+      arg = &t6;
+      args = sizeof (t6);    
+      break;
+    default:
+      GNUNET_break (0);
+      return;
+    } 
+
+  /* modify our published address list */
+  if (GNUNET_YES == add_remove)
+    {
+      plugin->env->notify_address (plugin->env->cls,
+                                   "tcp",
+                                   arg, args, GNUNET_TIME_UNIT_FOREVER_REL);
+      GNUNET_free_non_null (lal->external_nat_address);
+      lal->external_nat_address = GNUNET_memdup (arg, args);
+      lal->ena_size = args;
+    }
+  else
+    {
+      plugin->env->notify_address (plugin->env->cls,
+                                   "tcp",
+                                   arg, args, GNUNET_TIME_UNIT_ZERO);
+      GNUNET_free_non_null (lal->external_nat_address);
+      lal->ena_size = 0;
+    }
+}
+
+
 /**
  * Add the given address to the list of 'local' addresses, thereby
  * making it a 'legal' address for this peer to have.  
@@ -458,6 +568,10 @@ add_to_address_list (struct Plugin *plugin,
                     size_t arg_size)
 {
   struct LocalAddrList *lal;
+  struct sockaddr_in v4;
+  struct sockaddr_in6 v6;
+  const struct sockaddr *sa;
+  socklen_t salen;
 
   lal = plugin->lal_head;
   while (NULL != lal)
@@ -468,11 +582,47 @@ add_to_address_list (struct Plugin *plugin,
       lal = lal->next;
     }
   lal = GNUNET_malloc (sizeof (struct LocalAddrList) + arg_size);
+  lal->plugin = plugin;
   lal->size = arg_size;
   memcpy (&lal[1], arg, arg_size);
   GNUNET_CONTAINER_DLL_insert (plugin->lal_head,
                               plugin->lal_tail,
                               lal);
+  if (plugin->open_port == 0)
+    return; /* we're not listening at all... */
+  if (arg_size == sizeof (struct in_addr))
+    {
+      memset (&v4, 0, sizeof (v4));
+      v4.sin_family = AF_INET;
+      v4.sin_port = htons (plugin->open_port);
+      memcpy (&v4.sin_addr, arg, arg_size);
+#if HAVE_SOCKADDR_IN_SIN_LEN
+      v4.sin_len = sizeof (struct sockaddr_in);
+#endif
+      sa = (const struct sockaddr*) &v4;
+      salen = sizeof (v4);
+    }
+  else if (arg_size == sizeof (struct in6_addr))
+    {     
+      memset (&v6, 0, sizeof (v6));
+      v6.sin6_family = AF_INET6;
+      v6.sin6_port = htons (plugin->open_port);
+      memcpy (&v6.sin6_addr, arg, arg_size);
+#if HAVE_SOCKADDR_IN_SIN_LEN
+      v6.sin6_len = sizeof (struct sockaddr_in6);
+#endif
+      sa = (const struct sockaddr*) &v6;
+      salen = sizeof (v6);
+    }
+  else
+    {
+      GNUNET_break (0);
+      return;
+    }
+  if (plugin->allow_upnp)
+    lal->nat = GNUNET_NAT_register (sa, salen,
+                                   &nat_port_map_callback,
+                                   lal);
 }
 
 
@@ -503,6 +653,33 @@ check_local_addr (struct Plugin *plugin,
 }
 
 
+/**
+ * Check if the given address is in the list of 'mapped' addresses.
+ * 
+ * @param plugin the plugin
+ * @param arg the address, either a 'struct IPv4TcpAddress' or a 'struct IPv6TcpAddress'
+ * @param arg_size number of bytes in arg
+ * @return GNUNET_OK if this is one of our IPs, GNUNET_SYSERR if not
+ */
+static int
+check_mapped_addr (struct Plugin *plugin,
+                  const void *arg,
+                  size_t arg_size)
+{
+  struct LocalAddrList *lal;
+
+  lal = plugin->lal_head;
+  while (NULL != lal)
+    {
+      if ( (lal->ena_size == arg_size) &&
+          (0 == memcmp (lal->external_nat_address, arg, arg_size)) )
+       return GNUNET_OK;
+      lal = lal->next;
+    }
+  return GNUNET_SYSERR;
+}
+
+
 /**
  * Function called for a quick conversion of the binary address to
  * a numeric address.  Note that the caller must not free the
@@ -843,13 +1020,12 @@ disconnect_session (struct Session *session)
 #if DEBUG_TCP
   GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                   "tcp",
-                   "Disconnecting from `%4s' at %s (session %p).\n",
+                   "Disconnecting from `%4s' at %s.\n",
                    GNUNET_i2s (&session->target),
                    (session->connect_addr != NULL) ?
                    tcp_address_to_string (session->plugin,
                                          session->connect_addr,
-                                         session->connect_alen) : "*",
-                  session);
+                                         session->connect_alen) : "*");
 #endif
   /* remove from session list */
   prev = NULL;
@@ -880,8 +1056,7 @@ disconnect_session (struct Session *session)
                       "tcp",
                        pm->transmit_cont != NULL
                        ? "Could not deliver message to `%4s'.\n"
-                       :
-                       "Could not deliver message to `%4s', notifying.\n",
+                       : "Could not deliver message to `%4s', notifying.\n",
                        GNUNET_i2s (&session->target));
 #endif
       GNUNET_STATISTICS_update (session->plugin->env->stats,
@@ -969,6 +1144,13 @@ run_gnunet_nat_client (struct Plugin *plugin,
   char port_as_string[6];
   struct GNUNET_OS_Process *proc;
 
+  if (plugin->internal_address == NULL)
+    {
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Internal IP address not known, cannot use ICMP NAT traversal method\n"));
+      return;
+    }
   GNUNET_assert (sa->sin_family == AF_INET);
   if (NULL == inet_ntop (AF_INET,
                         &sa->sin_addr,
@@ -985,7 +1167,7 @@ run_gnunet_nat_client (struct Plugin *plugin,
   GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                   "tcp",
                   _("Running gnunet-nat-client %s %s %u\n"), 
-                  plugin->external_address,
+                  plugin->internal_address,
                   inet4,
                   (unsigned int) plugin->adv_port);
 #endif
@@ -993,7 +1175,7 @@ run_gnunet_nat_client (struct Plugin *plugin,
                                  NULL, 
                                  "gnunet-nat-client",
                                  "gnunet-nat-client",
-                                 plugin->external_address, 
+                                 plugin->internal_address, 
                                  inet4,
                                  port_as_string, 
                                  NULL);
@@ -1190,7 +1372,8 @@ tcp_plugin_send (void *cls,
 #endif
           session = create_session (plugin,
                                     target,
-                                    NULL, is_natd);
+                                    NULL, 
+                                   GNUNET_YES);
 
           /* create new message entry */
           pm = GNUNET_malloc (sizeof (struct PendingMessage) + msgbuf_size);
@@ -1210,7 +1393,10 @@ tcp_plugin_send (void *cls,
                                              session->pending_messages_tail,
                                              pm);
 
-          GNUNET_assert(GNUNET_CONTAINER_multihashmap_put(plugin->nat_wait_conns, &target->hashPubKey, session, GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY) == GNUNET_OK);
+          GNUNET_assert(GNUNET_CONTAINER_multihashmap_put(plugin->nat_wait_conns,
+                                                         &target->hashPubKey,
+                                                         session, 
+                                                         GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY) == GNUNET_OK);
 #if DEBUG_TCP_NAT
           GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                           "tcp",
@@ -1221,7 +1407,9 @@ tcp_plugin_send (void *cls,
           run_gnunet_nat_client (plugin, &a4);
           return 0;
         }
-      else if ((plugin->allow_nat == GNUNET_YES) && (is_natd == GNUNET_YES) && (GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, &target->hashPubKey)))
+      if ( (plugin->allow_nat == GNUNET_YES) && 
+          (is_natd == GNUNET_YES) && 
+          (GNUNET_YES == GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, &target->hashPubKey)) )
         {
           /* Only do one NAT punch attempt per peer identity */
           return -1;
@@ -1252,7 +1440,8 @@ tcp_plugin_send (void *cls,
       session = create_session (plugin,
                                target,
                                GNUNET_SERVER_connect_socket (plugin->server,
-                                                             sa), is_natd);
+                                                             sa), 
+                               GNUNET_NO);
       session->connect_addr = GNUNET_malloc (addrlen);
       memcpy (session->connect_addr,
              addr,
@@ -1465,24 +1654,19 @@ tcp_plugin_address_pretty_printer (void *cls,
 
 
 /**
- * Check if the given port is plausible (must be either
- * our listen port or our advertised port).  If it is
- * neither, we return GNUNET_SYSERR.
+ * Check if the given port is plausible (must be either our listen
+ * port or our advertised port), or any port if we are behind NAT
+ * and do not have a port open.  If it is neither, we return
+ * GNUNET_SYSERR.
  *
  * @param plugin global variables
  * @param in_port port number to check
  * @return GNUNET_OK if port is either open_port or adv_port
  */
 static int
-check_port (struct Plugin *plugin, uint16_t in_port)
+check_port (struct Plugin *plugin, 
+           uint16_t in_port)
 {
-  if ( (plugin->behind_nat == GNUNET_YES) && (in_port == 0) )
-    return GNUNET_OK;
-  if ( (plugin->only_nat_addresses == GNUNET_YES) &&
-       (plugin->behind_nat == GNUNET_YES) )
-    {
-      return GNUNET_SYSERR; /* odd case... */
-    }
   if ((in_port == plugin->adv_port) || (in_port == plugin->open_port))
     return GNUNET_OK;
   return GNUNET_SYSERR;
@@ -1522,14 +1706,15 @@ tcp_plugin_check_address (void *cls,
   if (addrlen == sizeof (struct IPv4TcpAddress))
     {
       v4 = (struct IPv4TcpAddress *) addr;
+      if (GNUNET_OK ==
+         check_mapped_addr (plugin, v4, sizeof (struct IPv4TcpAddress)))
+       return GNUNET_OK;
       if (GNUNET_OK !=
          check_port (plugin, ntohs (v4->t_port)))
        return GNUNET_SYSERR;
       if (GNUNET_OK !=
-         check_local_addr (plugin, &v4->ipv4_addr, sizeof (uint32_t)))
-       {
-         return GNUNET_SYSERR;
-       }
+         check_local_addr (plugin, &v4->ipv4_addr, sizeof (struct in_addr)))
+       return GNUNET_SYSERR;   
     }
   else
     {
@@ -1539,18 +1724,20 @@ tcp_plugin_check_address (void *cls,
          GNUNET_break_op (0);
          return GNUNET_SYSERR;
        }
+      if (GNUNET_OK ==
+         check_mapped_addr (plugin, v6, sizeof (struct IPv6TcpAddress)))
+       return GNUNET_OK;
       if (GNUNET_OK !=
          check_port (plugin, ntohs (v6->t6_port)))
        return GNUNET_SYSERR;
       if (GNUNET_OK !=
          check_local_addr (plugin, &v6->ipv6_addr, sizeof (struct in6_addr)))
-       {
-         return GNUNET_SYSERR;
-       }
+       return GNUNET_SYSERR;
     }
   return GNUNET_OK;
 }
 
+
 /**
  * We've received a nat probe from this peer via TCP.  Finish
  * creating the client session and resume sending of queued
@@ -1562,12 +1749,12 @@ tcp_plugin_check_address (void *cls,
  */
 static void
 handle_tcp_nat_probe (void *cls,
-                     struct GNUNET_SERVER_Client *client,
-                     const struct GNUNET_MessageHeader *message)
+                     struct GNUNET_SERVER_Client *client,
+                     const struct GNUNET_MessageHeader *message)
 {
   struct Plugin *plugin = cls;
   struct Session *session;
-  struct TCP_NAT_ProbeMessage *tcp_nat_probe;
+  const struct TCP_NAT_ProbeMessage *tcp_nat_probe;
   size_t alen;
   void *vaddr;
   struct IPv4TcpAddress *t4;
@@ -1591,84 +1778,93 @@ handle_tcp_nat_probe (void *cls,
       GNUNET_break_op(0);
       return;
     }
-  tcp_nat_probe = (struct TCP_NAT_ProbeMessage *)message;
-
-  if (GNUNET_CONTAINER_multihashmap_contains(plugin->nat_wait_conns, &tcp_nat_probe->clientIdentity.hashPubKey) == GNUNET_YES)
+  tcp_nat_probe = (const struct TCP_NAT_ProbeMessage *)message;
+  session = GNUNET_CONTAINER_multihashmap_get(plugin->nat_wait_conns, 
+                                             &tcp_nat_probe->clientIdentity.hashPubKey);
+  if (session == NULL)
     {
 #if DEBUG_TCP_NAT
-      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                       "tcp",
-                      "Found session for NAT probe!\n");
+                      "Did NOT find session for NAT probe!\n");
 #endif
-      session = GNUNET_CONTAINER_multihashmap_get(plugin->nat_wait_conns, &tcp_nat_probe->clientIdentity.hashPubKey);
-      GNUNET_assert(session != NULL);
-      GNUNET_assert(GNUNET_CONTAINER_multihashmap_remove(plugin->nat_wait_conns, &tcp_nat_probe->clientIdentity.hashPubKey, session) == GNUNET_YES);
-      GNUNET_SERVER_client_keep (client);
-      session->client = client;
-      session->last_activity = GNUNET_TIME_absolute_get ();
-      session->inbound = GNUNET_NO;
-
-      if (GNUNET_OK ==
-          GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
-        {
+      GNUNET_SERVER_receive_done (client, GNUNET_OK);
+      return;
+    }
 #if DEBUG_TCP_NAT
-          GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
-                          "tcp",
-                           "handle_tcp_nat_probe Found address `%s' for incoming connection %p\n",
-                           GNUNET_a2s (vaddr, alen),
-                           client);
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                  "tcp",
+                  "Found session for NAT probe!\n");
 #endif
-          if (((const struct sockaddr *)vaddr)->sa_family == AF_INET)
-            {
-              s4 = vaddr;
-              t4 = GNUNET_malloc (sizeof (struct IPv4TcpAddress));
-              t4->t_port = s4->sin_port;
-              t4->ipv4_addr = s4->sin_addr.s_addr;
-              session->connect_addr = t4;
-              session->connect_alen = sizeof (struct IPv4TcpAddress);
-            }
-          else if (((const struct sockaddr *)vaddr)->sa_family == AF_INET6)
-            {
-              s6 = vaddr;
-              t6 = GNUNET_malloc (sizeof (struct IPv6TcpAddress));
-              t6->t6_port = s6->sin6_port;
-              memcpy (&t6->ipv6_addr,
-                      &s6->sin6_addr,
-                      sizeof (struct in6_addr));
-              session->connect_addr = t6;
-              session->connect_alen = sizeof (struct IPv6TcpAddress);
-            }
-          else
-            {
+  GNUNET_assert(GNUNET_CONTAINER_multihashmap_remove(plugin->nat_wait_conns, 
+                                                    &tcp_nat_probe->clientIdentity.hashPubKey,
+                                                    session) == GNUNET_YES);
+  if (GNUNET_OK !=
+      GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
+    {
+      GNUNET_break (0);
+      GNUNET_free (session);
+      GNUNET_SERVER_receive_done (client, GNUNET_OK);
+      return;
+    }
+
+  GNUNET_SERVER_client_keep (client);
+  session->client = client;
+  session->last_activity = GNUNET_TIME_absolute_get ();
+  session->inbound = GNUNET_NO;
+
 #if DEBUG_TCP_NAT
-              GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
-                              "tcp",
-                              "Bad address for incoming connection!\n");
+  GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
+                  "tcp",
+                  "Found address `%s' for incoming connection\n",
+                  GNUNET_a2s (vaddr, alen));
 #endif
-            }
-          GNUNET_free (vaddr);
-        }
-
-      session->next = plugin->sessions;
-      plugin->sessions = session;
-      GNUNET_STATISTICS_update (plugin->env->stats,
-                                gettext_noop ("# TCP sessions active"),
-                                1,
-                                GNUNET_NO);
-      process_pending_messages (session);
-    }
-  else
-    {
+  switch (((const struct sockaddr *)vaddr)->sa_family)
+    {
+    case AF_INET:
+      s4 = vaddr;
+      t4 = GNUNET_malloc (sizeof (struct IPv4TcpAddress));
+      t4->t_port = s4->sin_port;
+      t4->ipv4_addr = s4->sin_addr.s_addr;
+      session->connect_addr = t4;
+      session->connect_alen = sizeof (struct IPv4TcpAddress);
+      break;
+    case AF_INET6:    
+      s6 = vaddr;
+      t6 = GNUNET_malloc (sizeof (struct IPv6TcpAddress));
+      t6->t6_port = s6->sin6_port;
+      memcpy (&t6->ipv6_addr,
+             &s6->sin6_addr,
+             sizeof (struct in6_addr));
+      session->connect_addr = t6;
+      session->connect_alen = sizeof (struct IPv6TcpAddress);
+      break;
+    default:
+      GNUNET_break_op (0);
 #if DEBUG_TCP_NAT
       GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                       "tcp",
-                      "Did NOT find session for NAT probe!\n");
+                      "Bad address for incoming connection!\n");
 #endif
+      GNUNET_free (vaddr);
+      GNUNET_SERVER_client_drop (client);
+      GNUNET_free (session);
+      GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
+      return;
     }
-
+  GNUNET_free (vaddr);
+  
+  session->next = plugin->sessions;
+  plugin->sessions = session;
+  GNUNET_STATISTICS_update (plugin->env->stats,
+                           gettext_noop ("# TCP sessions active"),
+                           1,
+                           GNUNET_NO);
+  process_pending_messages (session);
   GNUNET_SERVER_receive_done (client, GNUNET_OK);
 }
 
+
 /**
  * We've received a welcome from this peer via TCP.  Possibly create a
  * fresh client record and send back our welcome.
@@ -1695,9 +1891,9 @@ handle_tcp_welcome (void *cls,
 #if DEBUG_TCP
   GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                   "tcp",
-                   "Received %s message from a `%4s/%p'.\n",
+                   "Received %s message from `%4s'.\n",
                   "WELCOME",
-                   GNUNET_i2s (&wm->clientIdentity), client);
+                   GNUNET_i2s (&wm->clientIdentity));
 #endif
   GNUNET_STATISTICS_update (plugin->env->stats,
                            gettext_noop ("# TCP WELCOME messages received"),
@@ -1707,16 +1903,18 @@ handle_tcp_welcome (void *cls,
 
   if (session == NULL)
     {
-      GNUNET_SERVER_client_keep (client);
 #if DEBUG_TCP_NAT
       GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                       "tcp",
-                       "Received %s message from a `%4s/%p', creating session\n",
+                       "Received %s message from a `%4s', creating new session\n",
                        "WELCOME",
-                       GNUNET_i2s (&wm->clientIdentity), client);
+                       GNUNET_i2s (&wm->clientIdentity));
 #endif
+      GNUNET_SERVER_client_keep (client);
       session = create_session (plugin,
-                               &wm->clientIdentity, client, GNUNET_NO);
+                               &wm->clientIdentity,
+                               client,
+                               GNUNET_NO);
       session->inbound = GNUNET_YES;
       if (GNUNET_OK ==
          GNUNET_SERVER_client_get_address (client, &vaddr, &alen))
@@ -1724,9 +1922,8 @@ handle_tcp_welcome (void *cls,
 #if DEBUG_TCP_NAT
          GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                           "tcp",
-                          "Found address `%s' for incoming connection %p\n",
-                          GNUNET_a2s (vaddr, alen),
-                          client);
+                          "Found address `%s' for incoming connection\n",
+                          GNUNET_a2s (vaddr, alen));
 #endif
          if (alen == sizeof (struct sockaddr_in))
            {
@@ -1759,12 +1956,6 @@ handle_tcp_welcome (void *cls,
                           "Did not obtain TCP socket address for incoming connection\n");
 #endif
         }
-#if DEBUG_TCP
-      GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
-                      "tcp",
-                       "Creating new session %p for connection %p\n",
-                       session, client);
-#endif
       process_pending_messages (session);
     }
   else
@@ -1775,9 +1966,8 @@ handle_tcp_welcome (void *cls,
       {
         GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                         "tcp",
-                        "Found address `%s' (already have session) for incoming connection %p\n",
-                        GNUNET_a2s (vaddr, alen),
-                        client);
+                        "Found address `%s' (already have session)\n",
+                        GNUNET_a2s (vaddr, alen));
       }
 #endif
     }
@@ -1802,7 +1992,8 @@ handle_tcp_welcome (void *cls,
  * @param tc task context (unused)
  */
 static void
-delayed_done (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+delayed_done (void *cls, 
+             const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
   struct Session *session = cls;
   struct GNUNET_TIME_Relative delay;
@@ -1837,15 +2028,18 @@ handle_tcp_data (void *cls,
   struct Plugin *plugin = cls;
   struct Session *session;
   struct GNUNET_TIME_Relative delay;
+  uint16_t type;
 
-  if ((GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME == ntohs(message->type)) || (ntohs(message->type) == GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE))
+  type = ntohs (message->type);
+  if ( (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_WELCOME == type) || 
+       (GNUNET_MESSAGE_TYPE_TRANSPORT_TCP_NAT_PROBE == type) )
     {
       /* We don't want to propagate WELCOME and NAT Probe messages up! */
       GNUNET_SERVER_receive_done (client, GNUNET_OK);
       return;
     }
   session = find_session_by_client (plugin, client);
-  if ( (NULL == session) || (GNUNET_YES == session->expecting_welcome))
+  if ( (NULL == session) || (GNUNET_YES == session->expecting_welcome) )
     {
       GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
       return;
@@ -1897,13 +2091,12 @@ disconnect_notify (void *cls,
 #if DEBUG_TCP
   GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                   "tcp",
-                   "Destroying session of `%4s' with %s (%p) due to network-level disconnect.\n",
+                   "Destroying session of `%4s' with %s due to network-level disconnect.\n",
                    GNUNET_i2s (&session->target),
                    (session->connect_addr != NULL) ?
                    tcp_address_to_string (session->plugin,
                                          session->connect_addr,
-                                         session->connect_alen) : "*",
-                  client);
+                                         session->connect_alen) : "*");
 #endif
   disconnect_session (session);
 }
@@ -1911,7 +2104,7 @@ disconnect_notify (void *cls,
 
 /**
  * Add the IP of our network interface to the list of
- * our external IP addresses.
+ * our internal IP addresses.
  *
  * @param cls the 'struct Plugin*'
  * @param name name of the interface
@@ -1939,36 +2132,45 @@ process_interfaces (void *cls,
 
   af = addr->sa_family;
   arg_nat = NULL;
-  if (af == AF_INET)
+  switch (af)
     {
+    case AF_INET:
       t4.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
-      GNUNET_assert(NULL != inet_ntop(AF_INET, &t4.ipv4_addr, &buf[0], INET_ADDRSTRLEN));
-      if ((plugin->bind_address != NULL) && (0 != strcmp(buf, plugin->bind_address)))
+      GNUNET_assert (NULL != inet_ntop(AF_INET, 
+                                      &t4.ipv4_addr, 
+                                      buf, 
+                                      sizeof (buf)));
+      if ( (plugin->bind_address != NULL) && 
+          (0 != strcmp(buf, plugin->bind_address)) )
         {
+#if DEBUG_TCP
           GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
                           "tcp",
-                          "Not notifying transport of address %s\n",
+                          "Not notifying transport of address `%s' (redundant)\n",
                           GNUNET_a2s (addr, addrlen));
+#endif
           return GNUNET_OK;
         }
-      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (uint32_t));
-      if ((plugin->behind_nat == GNUNET_YES) && (plugin->only_nat_addresses == GNUNET_YES))
-        t4.t_port = htons(0);
-      else if (plugin->behind_nat == GNUNET_YES) /* We are behind NAT, but will advertise NAT and normal addresses */
+      if ( (plugin->internal_address == NULL) &&
+          (isDefault) )        
+       plugin->internal_address = GNUNET_strdup (buf); 
+      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (struct in_addr));
+      if (plugin->behind_nat == GNUNET_YES) 
         {
+         /* Also advertise as NAT (with port 0) */
           t4_nat.ipv4_addr = ((struct sockaddr_in *) addr)->sin_addr.s_addr;
-          t4_nat.t_port = htons(plugin->adv_port);
+          t4_nat.t_port = htons(0);
           arg_nat = &t4_nat;
-        }
-      else
-        t4.t_port = htons (plugin->adv_port);
+        }      
+      t4.t_port = htons (plugin->adv_port);    
       arg = &t4;
       args = sizeof (t4);
-    }
-  else if (af == AF_INET6)
-    {
+      break;
+    case AF_INET6:      
       if ( (IN6_IS_ADDR_LINKLOCAL (&((struct sockaddr_in6 *) addr)->sin6_addr)) || 
-          (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno(plugin->env->cfg, "transport-tcp", "DISABLEV6")) )
+          (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno(plugin->env->cfg, 
+                                                              "transport-tcp", 
+                                                              "DISABLEV6")) )
        {
          /* skip link local addresses */
          return GNUNET_OK;
@@ -1976,31 +2178,32 @@ process_interfaces (void *cls,
       memcpy (&t6.ipv6_addr,
              &((struct sockaddr_in6 *) addr)->sin6_addr,
              sizeof (struct in6_addr));
-      add_to_address_list (plugin, &t6.ipv6_addr, sizeof (struct in6_addr));
-      if ((plugin->behind_nat == GNUNET_YES) && (plugin->only_nat_addresses == GNUNET_YES))
-        t6.t6_port = htons(0);
-      else if (plugin->behind_nat == GNUNET_YES) /* We are behind NAT, but will advertise NAT and normal addresses */
+      add_to_address_list (plugin, 
+                          &t6.ipv6_addr, 
+                          sizeof (struct in6_addr));
+      if (plugin->behind_nat == GNUNET_YES)
         {
+         /* Also advertise as NAT (with port 0) */
           memcpy (&t6_nat.ipv6_addr,
                   &((struct sockaddr_in6 *) addr)->sin6_addr,
                   sizeof (struct in6_addr));
-          t6_nat.t6_port = htons(plugin->adv_port);
+          t6_nat.t6_port = htons(0);
           arg_nat = &t6;
         }
-      else
-        t6.t6_port = htons (plugin->adv_port);
+      t6.t6_port = htons (plugin->adv_port);
       arg = &t6;
       args = sizeof (t6);
-    }
-  else
-    {
+      break;
+    default:
       GNUNET_break (0);
       return GNUNET_OK;
     }
+#if DEBUG_TCP
   GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                   "tcp",
-                  _("Found address `%s' (%s) len %d\n"),
+                  "Found address `%s' (%s) len %d\n",
                    GNUNET_a2s (addr, addrlen), name, args);
+#endif
   plugin->env->notify_address (plugin->env->cls,
                                "tcp",
                                arg, args, GNUNET_TIME_UNIT_FOREVER_REL);
@@ -2044,30 +2247,41 @@ process_hostname_ips (void *cls,
   process_interfaces (plugin, "<hostname>", GNUNET_YES, addr, addrlen);
 }
 
+
 /**
  * We can now send a probe message, copy into buffer to really send.
  *
  * @param cls closure, a struct TCPProbeContext
  * @param size max size to copy
  * @param buf buffer to copy message to
+ * @return number of bytes copied into buf
  */
-static size_t notify_send_probe (void *cls,
-                                 size_t size, void *buf)
+static size_t
+notify_send_probe (void *cls,
+                  size_t size,
+                  void *buf)
 {
   struct TCPProbeContext *tcp_probe_ctx = cls;
+  struct Plugin *plugin = tcp_probe_ctx->plugin;
+  size_t ret;
 
+  tcp_probe_ctx->transmit_handle = NULL;
+  GNUNET_CONTAINER_DLL_remove (plugin->probe_head,
+                              plugin->probe_tail,
+                              tcp_probe_ctx);
   if (buf == NULL)
     {
-      return 0;
+      GNUNET_CONNECTION_destroy (tcp_probe_ctx->sock, GNUNET_NO);
+      GNUNET_free(tcp_probe_ctx);
+      return 0;    
     }
-
   GNUNET_assert(size >= sizeof(tcp_probe_ctx->message));
   memcpy(buf, &tcp_probe_ctx->message, sizeof(tcp_probe_ctx->message));
   GNUNET_SERVER_connect_socket (tcp_probe_ctx->plugin->server,
                                 tcp_probe_ctx->sock);
-
+  ret = sizeof(tcp_probe_ctx->message);
   GNUNET_free(tcp_probe_ctx);
-  return sizeof(tcp_probe_ctx->message);
+  return ret;
 }
 
 
@@ -2114,9 +2328,11 @@ tcp_plugin_server_read (void *cls,
   for (i = 0; i < sizeof(mybuf); i++)
     {
       if (mybuf[i] == '\n')
-        mybuf[i] = '\0';
-
-      if ((mybuf[i] == ':') && (i + 1 < sizeof(mybuf)))
+       {
+         mybuf[i] = '\0';
+         break;
+       }
+      if ( (mybuf[i] == ':') && (i + 1 < sizeof(mybuf)) )
         {
           mybuf[i] = '\0';
           port_start = &mybuf[i + 1];
@@ -2189,6 +2405,9 @@ tcp_plugin_server_read (void *cls,
          sizeof(struct GNUNET_PeerIdentity));
   tcp_probe_ctx->plugin = plugin;
   tcp_probe_ctx->sock = sock;
+  GNUNET_CONTAINER_DLL_insert (plugin->probe_head,
+                              plugin->probe_tail,
+                              tcp_probe_ctx);
   tcp_probe_ctx->transmit_handle 
     = GNUNET_CONNECTION_notify_transmit_ready (sock,
                                               ntohs (tcp_probe_ctx->message.header.size),
@@ -2207,40 +2426,53 @@ tcp_plugin_server_read (void *cls,
  * Start the gnunet-nat-server process for users behind NAT.
  *
  * @param plugin the transport plugin
- *
  * @return GNUNET_YES if process was started, GNUNET_SYSERR on error
  */
 static int
-tcp_transport_start_nat_server(struct Plugin *plugin)
+tcp_transport_start_nat_server (struct Plugin *plugin)
 {
+  if (plugin->internal_address == NULL)
+    return GNUNET_SYSERR;
   plugin->server_stdout = GNUNET_DISK_pipe (GNUNET_YES,
                                            GNUNET_NO,
                                            GNUNET_YES);
   if (plugin->server_stdout == NULL)
     return GNUNET_SYSERR;
-
 #if DEBUG_TCP_NAT
   GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG,
                   "tcp"
-                   "Starting gnunet-nat-server process cmd: %s %s\n", "gnunet-nat-server", plugin->internal_address);
+                   "Starting %s %s\n", 
+                  "gnunet-nat-server", 
+                  plugin->internal_address);
 #endif
   /* Start the server process */
-  plugin->server_proc = GNUNET_OS_start_process(NULL, plugin->server_stdout, "gnunet-nat-server", "gnunet-nat-server", plugin->internal_address, NULL);
+  plugin->server_proc = GNUNET_OS_start_process (NULL,
+                                                plugin->server_stdout,
+                                                "gnunet-nat-server", 
+                                                "gnunet-nat-server", 
+                                                plugin->internal_address, 
+                                                NULL);
   if (plugin->server_proc == NULL)
     {
-#if DEBUG_TCP_NAT
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                     "Failed to start gnunet-nat-server process\n");
-#endif
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Failed to start %s\n"),
+                      "gnunet-nat-server");
+      GNUNET_DISK_pipe_close (plugin->server_stdout);
+      plugin->server_stdout = NULL;    
       return GNUNET_SYSERR;
     }
   /* Close the write end of the read pipe */
-  GNUNET_DISK_pipe_close_end(plugin->server_stdout, GNUNET_DISK_PIPE_END_WRITE);
-
-  plugin->server_stdout_handle = GNUNET_DISK_pipe_handle(plugin->server_stdout, GNUNET_DISK_PIPE_END_READ);
-  plugin->server_read_task =
-      GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
-                                      plugin->server_stdout_handle, &tcp_plugin_server_read, plugin);
+  GNUNET_DISK_pipe_close_end(plugin->server_stdout, 
+                            GNUNET_DISK_PIPE_END_WRITE);
+  plugin->server_stdout_handle 
+    = GNUNET_DISK_pipe_handle (plugin->server_stdout, 
+                              GNUNET_DISK_PIPE_END_READ);
+  plugin->server_read_task 
+    = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
+                                      plugin->server_stdout_handle,
+                                     &tcp_plugin_server_read, 
+                                     plugin);
   return GNUNET_YES;
 }
 
@@ -2250,9 +2482,10 @@ tcp_transport_start_nat_server(struct Plugin *plugin)
  * PATH environment variable.
  *
  * @param binary the name of the file to find
+ * @return path to binary, NULL if not found
  */
 static char *
-get_path_from_PATH (char *binary)
+get_path_from_PATH (const char *binary)
 {
   char *path;
   char *pos;
@@ -2263,8 +2496,9 @@ get_path_from_PATH (char *binary)
   p = getenv ("PATH");
   if (p == NULL)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                 _("PATH environment variable is unset.\n"));
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                      _("PATH environment variable is unset.\n"));
       return NULL;
     }
   path = GNUNET_strdup (p);     /* because we write on it */
@@ -2293,24 +2527,26 @@ get_path_from_PATH (char *binary)
   return NULL;
 }
 
+
 /**
  * Check whether the suid bit is set on a file.
  * Attempts to find the file using the current
  * PATH environment variable as a search path.
  *
  * @param binary the name of the file to check
+ * @return GNUNET_YES if the file is SUID, 
+ *         GNUNET_NO if not, 
+ *         GNUNET_SYSERR on error
  */
 static int
-check_gnunet_nat_binary(char *binary)
+check_gnunet_nat_binary (const char *binary)
 {
   struct stat statbuf;
   char *p;
 #ifdef MINGW
   SOCKET rawsock;
-#endif
-
-#ifdef MINGW
   char *binaryexe;
+
   GNUNET_asprintf (&binaryexe, "%s.exe", binary);
   p = get_path_from_PATH (binaryexe);
   free (binaryexe);
@@ -2319,9 +2555,10 @@ check_gnunet_nat_binary(char *binary)
 #endif
   if (p == NULL)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                 _("Could not find binary `%s' in PATH!\n"),
-                 binary);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                      _("Could not find binary `%s' in PATH!\n"),
+                      binary);
       return GNUNET_NO;
     }
   if (0 != STAT (p, &statbuf))
@@ -2344,8 +2581,9 @@ check_gnunet_nat_binary(char *binary)
   if (INVALID_SOCKET == rawsock)
     {
       DWORD err = GetLastError ();
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, 
-                 "socket (AF_INET, SOCK_RAW, IPPROTO_ICMP) have failed! GLE = %d\n", err);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING, 
+                      "tcp",
+                      "socket (AF_INET, SOCK_RAW, IPPROTO_ICMP) failed! GLE = %d\n", err);
       return GNUNET_NO; /* not running as administrator */
     }
   closesocket (rawsock);
@@ -2353,6 +2591,7 @@ check_gnunet_nat_binary(char *binary)
 #endif
 }
 
+
 /**
  * Entry point for the plugin.
  *
@@ -2378,127 +2617,126 @@ libgnunet_plugin_transport_tcp_init (void *cls)
   unsigned int i;
   int behind_nat;
   int allow_nat;
-  int only_nat_addresses;
   char *internal_address;
   char *external_address;
   struct sockaddr_in in_addr;
   struct IPv4TcpAddress t4;
+  struct GNUNET_TIME_Relative idle_timeout;
 
-  service = GNUNET_SERVICE_start ("transport-tcp", env->cfg);
-  if (service == NULL)
+  behind_nat = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                    "transport-tcp",
+                                                    "BEHIND_NAT");
+  if ( (GNUNET_YES == behind_nat) &&
+       (GNUNET_YES != check_gnunet_nat_binary("gnunet-nat-server")) )
     {
+      behind_nat = GNUNET_NO;
       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                 _("Failed to start service for `%s' transport plugin.\n"),
-                 "tcp");
-      return NULL;
-    }
-
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
-                                                           "transport-tcp",
-                                                           "BEHIND_NAT"))
-    {
-      /* We are behind nat (according to the user) */
-      if (check_gnunet_nat_binary("gnunet-nat-server") == GNUNET_YES)
-        {
-          behind_nat = GNUNET_YES;
-        }
-      else
-        {
-          behind_nat = GNUNET_NO;
-          GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Configuration specified you are behind a NAT, but gnunet-nat-server is not installed properly (suid bit not set)!\n");
-        }
+                 _("Configuration requires `%s', but binary is not installed properly (SUID bit not set).  Option disabled.\n"),
+                 "gnunet-nat-server");        
     }
-  else
-    behind_nat = GNUNET_NO; /* We are not behind nat! */
 
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
-                                                           "transport-tcp",
-                                                           "ALLOW_NAT"))
+  allow_nat = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                   "transport-tcp",
+                                                   "ALLOW_NAT");
+  if ( (GNUNET_YES == allow_nat) &&
+       (GNUNET_YES != check_gnunet_nat_binary("gnunet-nat-client")) )
     {
-      if (check_gnunet_nat_binary("gnunet-nat-client") == GNUNET_YES)
-        allow_nat = GNUNET_YES; /* We will try to connect to NAT'd peers */
-      else
-      {
-        allow_nat = GNUNET_NO;
-        GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Configuration specified you want to connect to NAT'd peers, but gnunet-nat-client is not installed properly (suid bit not set)!\n");
-      }
+      allow_nat = GNUNET_NO;
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                 _("Configuration requires `%s', but binary is not installed properly (SUID bit not set).  Option disabled.\n"),
+                 "gnunet-nat-client"); 
     }
-  else
-    allow_nat = GNUNET_NO; /* We don't want to try to help NAT'd peers */
-
-
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
-                                                           "transport-tcp",
-                                                           "ONLY_NAT_ADDRESSES"))
-    only_nat_addresses = GNUNET_YES; /* We will only report our addresses as NAT'd */
-  else
-    only_nat_addresses = GNUNET_NO; /* We will report our addresses as NAT'd and non-NAT'd */
-
+  
   external_address = NULL;
-  if (((GNUNET_YES == behind_nat) || (GNUNET_YES == allow_nat)) && (GNUNET_OK !=
-         GNUNET_CONFIGURATION_get_value_string (env->cfg,
-                                                "transport-tcp",
-                                                "EXTERNAL_ADDRESS",
-                                                &external_address)))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                       _
-                       ("Require EXTERNAL_ADDRESS for service `%s' in configuration (either BEHIND_NAT or ALLOW_NAT set to YES)!\n"),
-                       "transport-tcp");
-      GNUNET_SERVICE_stop (service);
-      return NULL;
+  if (GNUNET_OK ==
+      GNUNET_CONFIGURATION_have_value (env->cfg,
+                                      "transport-tcp",
+                                      "EXTERNAL_ADDRESS"))
+    {
+      (void) GNUNET_CONFIGURATION_get_value_string (env->cfg,
+                                                   "transport-tcp",
+                                                   "EXTERNAL_ADDRESS",
+                                                   &external_address);
     }
 
-  if ((external_address != NULL) && (inet_pton(AF_INET, external_address, &in_addr.sin_addr) != 1))
+  if ( (external_address != NULL) && 
+       (inet_pton(AF_INET, external_address, &in_addr.sin_addr) != 1) ) 
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Malformed EXTERNAL_ADDRESS %s given in configuration!\n", external_address);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Malformed %s `%s' given in configuration!\n"), 
+                      "EXTERNAL_ADDRESS",
+                      external_address);
+      return NULL;   
     }
 
   internal_address = NULL;
-  if ((GNUNET_YES == behind_nat) && (GNUNET_OK !=
-         GNUNET_CONFIGURATION_get_value_string (env->cfg,
-                                                "transport-tcp",
-                                                "INTERNAL_ADDRESS",
-                                                &internal_address)))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                 _("Require INTERNAL_ADDRESS for service `%s' in configuration!\n"),
-                 "transport-tcp");
-      GNUNET_SERVICE_stop (service);
-      GNUNET_free_non_null(external_address);
-      return NULL;
+  if (GNUNET_OK ==
+      GNUNET_CONFIGURATION_have_value (env->cfg,
+                                      "transport-tcp",
+                                      "INTERNAL_ADDRESS"))
+    {
+      (void) GNUNET_CONFIGURATION_get_value_string (env->cfg,
+                                                   "transport-tcp",
+                                                   "INTERNAL_ADDRESS",
+                                                   &internal_address);
     }
 
-  if ((internal_address != NULL) && (inet_pton(AF_INET, internal_address, &in_addr.sin_addr) != 1))
+  if ( (internal_address != NULL) && 
+       (inet_pton(AF_INET, internal_address, &in_addr.sin_addr) != 1) )
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_WARNING, "Malformed INTERNAL_ADDRESS %s given in configuration!\n", internal_address);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                      "tcp",
+                      _("Malformed %s `%s' given in configuration!\n"), 
+                      "INTERNAL_ADDRESS",
+                      internal_address);      
+      GNUNET_free_non_null(internal_address);
+      GNUNET_free_non_null(external_address);
+      return NULL;
     }
 
   aport = 0;
-  if ((GNUNET_OK !=
-       GNUNET_CONFIGURATION_get_value_number (env->cfg,
-                                              "transport-tcp",
-                                              "PORT",
-                                              &bport)) ||
-      (bport > 65535) ||
-      ((GNUNET_OK ==
-        GNUNET_CONFIGURATION_get_value_number (env->cfg,
-                                               "transport-tcp",
-                                               "ADVERTISED-PORT",
-                                               &aport)) && (aport > 65535)))
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                       _
-                       ("Require valid port number for service `%s' in configuration!\n"),
+  if ( (GNUNET_OK !=
+       GNUNET_CONFIGURATION_get_value_number (env->cfg,
+                                              "transport-tcp",
+                                              "PORT",
+                                              &bport)) ||
+       (bport > 65535) ||
+       ((GNUNET_OK ==
+        GNUNET_CONFIGURATION_get_value_number (env->cfg,
+                                               "transport-tcp",
+                                               "ADVERTISED-PORT",
+                                               &aport)) && 
+       (aport > 65535)) )
+    {
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                       _("Require valid port number for service `%s' in configuration!\n"),
                        "transport-tcp");
       GNUNET_free_non_null(external_address);
       GNUNET_free_non_null(internal_address);
-      GNUNET_SERVICE_stop (service);
       return NULL;
     }
 
   if (aport == 0)
     aport = bport;
+  if (bport == 0)
+    aport = 0;
+
+  if (bport != 0)
+    {
+      service = GNUNET_SERVICE_start ("transport-tcp", env->cfg);
+      if (service == NULL)
+       {
+         GNUNET_log_from (GNUNET_ERROR_TYPE_WARNING,
+                          "tcp",
+                          _("Failed to start service.\n"));
+         return NULL;
+       }
+    }
+  else
+    service = NULL;
+
   plugin = GNUNET_malloc (sizeof (struct Plugin));
   plugin->open_port = bport;
   plugin->adv_port = aport;
@@ -2506,7 +2744,9 @@ libgnunet_plugin_transport_tcp_init (void *cls)
   plugin->internal_address = internal_address;
   plugin->behind_nat = behind_nat;
   plugin->allow_nat = allow_nat;
-  plugin->only_nat_addresses = only_nat_addresses;
+  plugin->allow_upnp = GNUNET_CONFIGURATION_get_value_yesno (env->cfg,
+                                                            "transport-tcp",
+                                                            "ENABLE_UPNP");
   plugin->env = env;
   plugin->lsock = NULL;
   api = GNUNET_malloc (sizeof (struct GNUNET_TRANSPORT_PluginFunctions));
@@ -2517,55 +2757,91 @@ libgnunet_plugin_transport_tcp_init (void *cls)
   api->check_address = &tcp_plugin_check_address;
   api->address_to_string = &tcp_address_to_string;
   plugin->service = service;
-  plugin->server = GNUNET_SERVICE_get_server (service);
+  if (service != NULL)   
+    {
+      plugin->server = GNUNET_SERVICE_get_server (service);
+    }
+  else
+    {
+      if (GNUNET_OK !=
+         GNUNET_CONFIGURATION_get_value_time (env->cfg,
+                                              "transport-tcp",
+                                              "TIMEOUT",
+                                              &idle_timeout))
+       {
+         GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                          "tcp",
+                          _("Failed to find option %s in section %s!\n"),
+                          "TIMEOUT",
+                          "transport-tcp");
+         GNUNET_free_non_null(external_address);
+         GNUNET_free_non_null(internal_address);
+         GNUNET_free (api);
+         return NULL;
+       }
+      plugin->server = GNUNET_SERVER_create_with_sockets (NULL, NULL, NULL,
+                                                         idle_timeout, GNUNET_YES);
+    }
   plugin->handlers = GNUNET_malloc (sizeof (my_handlers));
   memcpy (plugin->handlers, my_handlers, sizeof (my_handlers));
   for (i = 0;
-       i <
-       sizeof (my_handlers) / sizeof (struct GNUNET_SERVER_MessageHandler);
+       i < sizeof (my_handlers) / sizeof (struct GNUNET_SERVER_MessageHandler);
        i++)
     plugin->handlers[i].callback_cls = plugin;
   GNUNET_SERVER_add_handlers (plugin->server, plugin->handlers);
+  GNUNET_SERVER_disconnect_notify (plugin->server,
+                                  &disconnect_notify,
+                                  plugin);    
+  GNUNET_OS_network_interfaces_list (&process_interfaces, plugin);
 
-  if (plugin->behind_nat == GNUNET_YES)
+  if ( (plugin->behind_nat == GNUNET_YES) &&
+       (GNUNET_YES != tcp_transport_start_nat_server(plugin)) )
     {
-      if (GNUNET_YES != tcp_transport_start_nat_server(plugin))
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-
-                           _
-                           ("Failed to start %s required for NAT in %s!\n"),
-                           "gnunet-nat-server"
-                           "transport-tcp");
-          GNUNET_free_non_null(external_address);
-          GNUNET_free_non_null(internal_address);
-          GNUNET_SERVICE_stop (service);
-         GNUNET_free (api);
-          return NULL;
-        }
+      GNUNET_log_from (GNUNET_ERROR_TYPE_ERROR,
+                      "tcp",
+                      _("Failed to start %s required for NAT in %s!\n"),
+                      "gnunet-nat-server"
+                      "transport-tcp");
+      GNUNET_free_non_null(external_address);
+      GNUNET_free_non_null(internal_address);
+      if (service != NULL)
+       GNUNET_SERVICE_stop (service);
+      else
+       GNUNET_SERVER_destroy (plugin->server);
+      GNUNET_free (api);
+      return NULL;
     }
 
   if (allow_nat == GNUNET_YES)
     {
-      plugin->nat_wait_conns = GNUNET_CONTAINER_multihashmap_create(100);
-      GNUNET_assert(plugin->nat_wait_conns != NULL);
+      plugin->nat_wait_conns = GNUNET_CONTAINER_multihashmap_create(16);
+      GNUNET_assert (plugin->nat_wait_conns != NULL);
     }
 
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO, _("TCP transport listening on port %llu\n"), bport);
+  if (bport != 0)
+    GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, 
+                    "tcp",
+                    _("TCP transport listening on port %llu\n"), 
+                    bport);
+  else
+    GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, 
+                    "tcp",
+                    _("TCP transport not listening on any port (client only)\n"));
   if (aport != bport)
-    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+    GNUNET_log_from (GNUNET_ERROR_TYPE_INFO,
+                    "tcp",
                      _("TCP transport advertises itself as being on port %llu\n"),
                      aport);
-  GNUNET_SERVER_disconnect_notify (plugin->server,
-                                  &disconnect_notify,
-                                   plugin);
-
-  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_string (env->cfg, "transport-tcp", "BINDTO", &plugin->bind_address))
-    GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Binding tcp plugin to specific address: `%s'\n", plugin->bind_address);
 
-  if (plugin->behind_nat == GNUNET_NO)
+  if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_string (env->cfg,
+                                                          "transport-tcp", 
+                                                          "BINDTO", 
+                                                          &plugin->bind_address))
     {
-      GNUNET_OS_network_interfaces_list (&process_interfaces, plugin);
+      GNUNET_log_from (GNUNET_ERROR_TYPE_INFO, 
+                      "tcp",
+                      _("Binding TCP plugin to specific address: `%s'\n"), 
+                      plugin->bind_address);
     }
 
   plugin->hostname_dns = GNUNET_RESOLVER_hostname_resolve (env->cfg,
@@ -2574,25 +2850,33 @@ libgnunet_plugin_transport_tcp_init (void *cls)
                                                            &process_hostname_ips,
                                                            plugin);
 
-  if ((plugin->behind_nat == GNUNET_YES) && (inet_pton(AF_INET, plugin->external_address, &t4.ipv4_addr) == 1))
+  if ( (plugin->external_address != NULL) && 
+       (inet_pton(AF_INET,
+                 plugin->external_address, 
+                 &t4.ipv4_addr) == 1) )
     {
-      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Notifying transport of address %s:0\n", plugin->external_address);
-      t4.t_port = htons(0);
-      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (uint32_t));
-      plugin->env->notify_address (plugin->env->cls,
-                                  "tcp",
-                                   &t4, sizeof(t4), GNUNET_TIME_UNIT_FOREVER_REL);
-    }
-  else if ((plugin->external_address != NULL) && (inet_pton(AF_INET, plugin->external_address, &t4.ipv4_addr) == 1))
-    {
-      t4.t_port = htons(plugin->adv_port);
-      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Notifying transport of address %s:%d\n", plugin->external_address, plugin->adv_port);
-      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (uint32_t));
+      if (plugin->behind_nat == GNUNET_YES) 
+       {
+         GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                          "tcp",
+                          "Notifying transport of address %s:0\n", 
+                          plugin->external_address);
+         t4.t_port = htons(0);
+       }
+      else
+       {
+         t4.t_port = htons(plugin->adv_port);
+         GNUNET_log_from (GNUNET_ERROR_TYPE_DEBUG, 
+                          "tcp",
+                          "Notifying transport of address %s:%d\n",
+                          plugin->external_address, 
+                          plugin->adv_port);
+       }
+      add_to_address_list (plugin, &t4.ipv4_addr, sizeof (struct in_addr));
       plugin->env->notify_address (plugin->env->cls,
-                                   "tcp",
-                                   &t4, sizeof(t4), GNUNET_TIME_UNIT_FOREVER_REL);
+                                  "tcp",
+                                  &t4, sizeof(t4), GNUNET_TIME_UNIT_FOREVER_REL);
     }
-
   return api;
 }
 
@@ -2607,6 +2891,7 @@ libgnunet_plugin_transport_tcp_done (void *cls)
   struct Plugin *plugin = api->cls;
   struct Session *session;
   struct LocalAddrList *lal;
+  struct TCPProbeContext *tcp_probe;
 
   while (NULL != (session = plugin->sessions))
     disconnect_session (session);
@@ -2615,15 +2900,29 @@ libgnunet_plugin_transport_tcp_done (void *cls)
       GNUNET_RESOLVER_request_cancel (plugin->hostname_dns);
       plugin->hostname_dns = NULL;
     }
-  GNUNET_SERVICE_stop (plugin->service);
+  if (plugin->service != NULL)
+    GNUNET_SERVICE_stop (plugin->service);
+  else
+    GNUNET_SERVER_destroy (plugin->server);
   GNUNET_free (plugin->handlers);
   while (NULL != (lal = plugin->lal_head))
     {
       GNUNET_CONTAINER_DLL_remove (plugin->lal_head,
                                   plugin->lal_tail,
                                   lal);
+      if (lal->nat != NULL)
+       GNUNET_NAT_unregister (lal->nat);
+      GNUNET_free_non_null (lal->external_nat_address);
       GNUNET_free (lal);
     }
+  while (NULL != (tcp_probe = plugin->probe_head))
+    {
+      GNUNET_CONTAINER_DLL_remove (plugin->probe_head,
+                                  plugin->probe_tail,
+                                  tcp_probe);
+      GNUNET_CONNECTION_destroy (tcp_probe->sock, GNUNET_NO);
+      GNUNET_free (tcp_probe);
+    }
 
   if (plugin->behind_nat == GNUNET_YES)
     {